Update legacy versions of StyleLint

[blackfalcon]

General Support Request

 ◯ stylelint devDep                     13.13.1  ❯  15.10.3  https://stylelint.io
 ◯ stylelint-config-recommended devDep  5.0.0    ❯  13.0.0   https://github.com/stylelint/stylelint-config-recommended#readme
 ◯ stylelint-config-standard devDep     22.0.0   ❯  34.0.0   https://github.com/stylelint/stylelint-config-standard#readme

Support request

Update the repo and Sass code to support the latest versions of stylelint

Exit criteria

This issue can be closed once the repo's dependencies have been updated and the Sass code complies to the new stylelint rules.

[blackfalcon]

It is assumed that stylelint has dependencies on a series of deprecated resources. While this update is only affecting our testing harness, there is some risk in maintaining this legacy version of the dependency.

npm WARN deprecated source-map-url@0.4.1: See https://github.com/lydell/source-map-url#deprecated
npm WARN deprecated @stylelint/postcss-markdown@0.36.2: Use the original unforked package instead: postcss-markdown
npm WARN deprecated urix@0.1.0: Please see https://github.com/lydell/urix#deprecated
npm WARN deprecated opn@6.0.0: The package has been renamed to `open`
npm WARN deprecated source-map-resolve@0.6.0: See https://github.com/lydell/source-map-resolve#deprecated
npm WARN deprecated resolve-url@0.2.1: https://github.com/lydell/resolve-url#deprecated
npm WARN deprecated source-map-resolve@0.5.3: See https://github.com/lydell/source-map-resolve#deprecated
npm WARN deprecated circular-json@0.3.3: CircularJSON is in maintenance only, flatted is its successor.
npm WARN deprecated chokidar@2.1.8: Chokidar 2 does not receive security updates since 2019. Upgrade to chokidar 3 with 15x fewer dependencies
npm WARN deprecated fsevents@1.2.13: fsevents 1 will break on node v14+ and could be using insecure binaries. Upgrade to fsevents 2.
npm WARN deprecated uuid@3.4.0: Please upgrade  to version 7 or higher.  Older versions may use Math.random() in certain circumstances, which is known to be problematic.  See https://v8.dev/blog/math-random for details.
npm WARN deprecated core-js@2.6.12: core-js@<3.23.3 is no longer maintained and not recommended for usage due to the number of issues. Because of the V8 engine whims, feature detection in old core-js versions could cause a slowdown up to 100x even if nothing is polyfilled. Some versions have web compatibility issues. Please, upgrade your dependencies to the actual version of core-js.